The present invention relates to rotary valves used in fluid transport pipelines in the semiconductor industry, the biopharmaceutical industry, the food industry or in other chemical industries; more specifically, it relates to a rotary valve in which the degree of aperture can be fixed by a locking mechanism, whereby misoperation can be prevented, the locking mechanism being compact and requiring little space, so that even if the valve is mounted in small spaces, there is no impediment to turning the handle, whereby a single valve body can easily be converted to one that has a locking mechanism or to one that does not have a locking mechanism, by replacing the handle alone, and whereby, in a rotary valve having at least three flow paths, opening, closing and switching of flow paths can be maintained locked at reliable switching positions.
Conventional rotary valves often did not have locking mechanisms and, in order to prevent operation in such cases, methods were employed such as installing warning signs, removing the handle, fixing the handle in place with string or wire, or providing a cover.
Furthermore, valves having handle locking mechanisms were structurally specialized, as they required that the valve body have a special structure, such as that shown in FIG. 18. This valve is an on-off valve having a structure in which: opening and closing is controlled by rotationally operating a valve element by way of a valve stem 103, as result of turning a handle lever 101 in a direction X; a locking plate 102, which turns in a direction Y, in a plane substantially perpendicular to the direction X in which the handle lever 101 turns, is pivotably supported on the upright section of the handle lever 101; and the valve is locked open or closed as a result of latching the locking plate in a latch lock 104, by way of the spring force of a tensioning spring 105, which is mounted under tension between the handle lever 101 and the locking plate 102 (For example, see Patent Reference 1).
Furthermore, the rotary valve shown in FIG. 19 is an on-off valve in which opening and closing of the valve is controlled by turning a handle 107, and which is structured so that the valve is locked open or closed by engaging a protrusion 110, at the inner part of the bottom of the handle 107, and a notch 111, which is provided on the neck of the valve body 112, wherein by pulling up an engaging member 108 at the bottom of the grip of the handle 107, the aforementioned engagement is released, so that the handle 107 turns and the valve is opened or closed; furthermore, this can be maintained locked by inserting a cylinder lock or the like into a hole 109 (For example, see Patent Reference 2).    Patent Reference 1: JP-08-303637-A (pp. 1-6, FIG. 1)    Patent Reference 2: U.S. Pat. No. 6,260,819 (pp. 1-7. FIG. 1)
However, with the valve shown in FIG. 18, because the latch lock 104 must be provided on the valve sleeve 106, it is difficult to provide the latch lock 104 as part of follow up work, so that it is not possible to install the locking mechanism on existing valves that do not have a latch lock 104; thus, if one wished to use valves that had been already been installed on pipes as valves having open/closed locking mechanisms, the valves would have to be removed from the pipes and replaced with valves equipped with locking mechanisms. Furthermore, there was a problem in so much as the structure did not readily allow the locking plate 102 to be fastened in the locked state with a cylinder lock or the like, and therefore this was not suited to installation in places where any number of people could touch it.
Next, with the rotary valve shown in FIG. 19, there are problems in so much as a specialized valve body is required, on which the notch 111 is provided for use in the locking mechanism; and because the specialized handle that has the engaging member 108 is elongated in the valve stem direction, it is difficult to install this in small spaces.
Furthermore, in the rotary valve having the locking mechanism described above, because the notch 111 must be provided on the valve body 112, it may be difficult to provide the notch 111 as part of follow up work, and therefore the locking mechanism can not be installed on existing valves that do not have the notch 111; thus, if one wished to use valves that had been installed on pipes as valves having open/closed locking mechanisms, the valves would have to be removed from the pipes and replaced with valves having locking mechanisms; consequently, it would not be possible to perform the replacement work without temporarily stopping the flow of the fluid within the pipes; furthermore, because the valve is larger than one having a conventional handle that does not include a locking mechanism, there was a problem in that this could not easily be used for replacements in places where there was little space for valve installation.